Managed Object Placement Service

John Bresnahan, Mike Link and Raj Kettimuthu

(Presenting)

Argonne National Lab

Topics for discussion

MOPS overview MOPS 0.1

Pipelining Gfork GridFTP plugin for Gfork Lotman

Other GridFTP enhancements Performance Ease of use

Future directions

Managed Object Placement Service (MOPS)

Resource management in GridFTP Memory usage limitation Enforce appropriate storage usage Enforce appropriate bandwidth usage Eliminates the potential to *overheat* a system

Bandwidth and storage reservation Transfer scheduling MOPS 0.1 is available at

http://www.cedps.net/wiki/index.php/Software

MOPS

MOPS 0.1 includes Optimization for lots of small files transfer

Globus fork (Gfork) - inetd like service that allows state to be maintained across connections

GridFTP plugin for Gfork - allows for dynamic addition/removal of data movers, limit memory usage

Lotman - manage storage Plugin for GridFTP to enforce storage usage policies using lotman

Lots of Small Files (LOSF) Problem

GridFTP and FTP - command response protocols

A client must wait for a “Finished response” before sending the next command

Overhead added on a per file basis Performance is best on large files

Overhead has less impact Performance suffers for a large data set partitioned into many small files

LOSF

Traditional data transfer pattern

File Request 1

File Request 2

File Request 3

DATA 1

DATA 2

DATA 3

ACK 1

ACK 2

ACK 3

Pipelining

Data transfer pattern with pipelining

File Request 1

File Request 2File Request 3

DATA 1

DATA 2

DATA 3

ACK 1

ACK 2

ACK 3

Pipelining

WAN - SDSC and ANL with GSI security

Gfork

Under extreme loads it is possible that GridFTP servers require more memory than the system has and cause the system to fall over

Developed a service called gfork to help avoid this situation

Gfork - a service like inetd that listens on a TCP port and runs a configurable executable in a child process whenever a connection is made

Allows server state to be maintained across connections

Gfork

Associated with Gfork is a user defined master process Master process runs for the lifetime of the gfork daemon

Client

Server Host

GForkServer

GridFTPPlugin

GridFTP Server Instance

Fork

GridFTP Server Instance

GridFTP Server Instance

State Sharing Link

ClientClient Inherited Links

Control Channel Connections

Dynamic data movers

GridFTP can be run as a striped server - there is a control process and several data movers.

The data movers run in tandem to transfer files faster by tying together many NICs.

When the control process is run out of inetd the list of possible data movers had to be statically configured.

But data movers tend to come and go. Sometimes data movers fail Sometimes data movers are added to a pool

Dynamic data movers

GridFTP plugin for Gfork allows for dynamic addition/removal of data movers

GridFTP plugin on the control node can be configured to listen for data mover registrations

GridFTP plugin on the data movers can be configured to register with the plugin on the control node

Dynamic data movers Control node

GForkServer

GridFTPPlugin

Frontend Instance

Fork Lookup available

backend

BackendInstance

Data Mover

Fork

Registration

Control Connection

Multiple data movers register with plugin

Plugin maintains the list of available DMs

Control process instance selects N DMs for use

If any one DM fails another can be used DM pool can grow and shrink

GForkServer

GridFTPPlugin

Memory Management

GridFTP plugin for Gfork has a memory limiting option

Limit memory usage to a given value or to the maximum amount of RAM in the system.

Most of the memory is given to the first few connections

When the plugin detects that it is overloaded, each session is limited to half the available memory.

Memory Management

To measure the effectiveness of the memory limiting functionality, we performed experiments using xen VM.

Clients are run on a 2GHz processor with 512MB of RAM and the server was run in a xen VM with either 64MB or 128MB of RAM with a 2GHz AMD 64bit processor.

The machines were connected to each other via a 1Gb/s network with iperf measured max speeds of 600Mb/s.

No memory limiting

With memory limiting

Lotman

Manage disk space - interface to create disk space called lot

Lot defined by four characteristics Owner, capacity, duration, files Owner - client that is allowed to use the lot

Capacity - amount of data that can be stored

Duration - time a lot is guaranteed to exist

Lot contains a set of files

GridFTP with lotman

Client

GridFTP Server

Storage Access Control Plugin

DSI Plugin

Main Codebase

Lotman

Other Enhancements

Performance enhancement GridFTP over UDT

Ease of Use enhancements Alternate security mechanism GridFTP Where there’s FTP

GridFTP over UDT

UDT is an application-level data transport protocol that uses UDP to transfer data

Implement its own reliability and congestion control mechanisms

Achieves good performance on high-bandwidth, high-delay networks where TCP has significant limitations

GridFTP uses Globus XIO interface to invoke network I/O operations

GridFTP over UDT

XIO framework presents a standard open/close/read/write interface to many different protocol implementations including TCP, UDP, HTTP -- and now UDT

The protocol implementations are called drivers. A driver can be dynamically loaded and stacked by any

Globus XIO application.

Created an XIO driver for UDT reference implementation

Enabled GridFTP to use it as an alternate transport protocol

GridFTP over UDT

Argonne to NZ Throughput in Mbit/s

Argonne to LA Throughput in Mbit/s

Iperf – 1 stream 19.7 74.5

Iperf – 8 streams 40.3 117.0

GridFTP mem TCP – 1 stream 16.4 63.8

GridFTP mem TCP – 8 streams 40.2 112.6

GridFTP disk TCP – 1 stream 16.3 59.6

GridFTP disk TCP – 8 streams 37.4 102.4

GridFTP mem UDT 179.3 396.6

GridFTP disk UDT 178.6 428.3

UDT mem 201.6 432.5

UDT disk 162.5 230.0

Alternate security mechanism GridFTP traditionally uses GSI for

establishing secure connections In some situations, preferable to use SSH

security mechanism Leverages the fact that an SSH client can

remotely execute programs by forming a secure connection with SSHD The client (globus-url-copy) acts as an SSH client and remotely executes a Globus GridFTP server

All of the standard IO from the remote program is routed back to the client.

SSH security mechanism Client support for using SSH is automatically

enabled On the server side (where you intend the client

to remotely execute a server) setup-globus-gridftp-sshftp -server

In order to use SSH as a security mechanism, the user must provide urls that begin with sshftp:// as arguments. globus-url-copy sshftp://<host>:<port>/<filepath> file:/<filepath>

<port> is the port in which sshd listens on the host referred to by <host> (the default value is 22).

GridFTP Where there’s FTP (GWFTP)

GridFTP has been in existence for some time and has proven to be quite robust and useful

Only few GridFTP clients available FTP has innumerable clients GWFTP - created to leverage the FTP clients

A proxy between FTP clients and GridFTP servers

GWFTP

Two security options provided with GWFTP to authenticate its client Password based and host based

FTP Client

GWFTP(GSI

Credential)

wiggum.mcs.anl.govGridFTP Server

(2811)

USER <GWFTP username> ::gsiftp://wiggum.mcs.anl.gov:2811/

PASS GSI Authentication

Get request

Get request

DataData

Future direction

Controller

Network reservation

serviceEnhanced GridFTP

Storage Manager

Controller

Enhance GridFTP servers to expose status as WS resource properties Take advantage of the network provisioning services

Collaborating with Terapath and LambdaStation projects

Infiniband over SONET

Need specialized hardware: Obsidian longbow 1. IB over SONET/Ethernet – frame conversion2. Buffer-based termination of IB flow control

LinuxhostLinuxhost

ORNL700 miles

LinuxhostLinuxhost

ChicagoChicagoCDCICDCI

ChicagoChicagoCDCICDCI

SeattleSeattleCDCICDCISeattleSeattleCDCICDCI

SunnyvaleSunnyvaleCDCICDCI

SunnyvaleSunnyvaleCDCICDCI

ORNLORNLCDCICDCIORNLORNLCDCICDCI

longbowlongbowIB/SIB/S

longbowlongbowIB/SIB/S

longbowlongbowIB/SIB/S

longbowlongbowIB/SIB/S

3300 miles4300 miles

ORNL loop -0.2 mile: 7.5Gbps

IB 4x: 8Gbps (full speed)Host-to-host local switch:7.5Gbps

IB 4x

ORNL-Chicago loop – 1400 miles: 7.46Gbps

ORNL- Chicago - Seattle loop – 6600 miles: 7.23Gbps

ORNL – Chicago – Seattle - Sunnyvale loop – 8600 miles: 7.20Gbps

GridFTP over Infiniband

Can use infiniband through Sockets Direct Protocol (SDP)

SDP provides a socket interface for Open Fabrics software stack (a standard implemented by infiniband and iwarp) No kernel bypass

User level verbs to interface directly with infiniband hardware Develop a XIO driver for verbs interface